Saturday, September 23, 2023

Precision-Guided Munitions: Radar-Guided Weapons (Part 4 of 4)

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Fig. 6: MIM-104 Patriot immediately after launch
Fig. 6: MIM-104 Patriot immediately after launch
Fig. 7: RIM-174 Standard ERAM (SM-6) in flight
Fig. 7: RIM-174 Standard ERAM (SM-6) in flight

The first operational use of AIM-7 Sparrow was during Vietnamese war in June 1965 when the US Navy shot down two North Vietnamese MiG-17s. Due to the absence of an IFF system on the launch aircraft, long-range capability of these missiles could not be used.

First missiles had a kill probability of only 10 per cent. This problem was subsequently overcome in AIM-7E. The last use of AIM-7 Sparrow was in Operation Desert Storm in 1991, where it was extensively and successfully used on F-15 and F-16 fighter aircrafts. The missile has been on the inventory of armed forces of a large number of countries including Australia, Canada, Israel, Italy, Japan, South Korea, Spain, Taiwan, Turkey, the UK and the USA. Fig. 5 shows AIM-7 Sparrow being launched from F-18A fighter aircraft.

MIM-104 Patriot, manufactured by Raytheon, is a long-range, all-altitude, all-weather air defence system to counter tactical ballistic missiles, cruise missiles and advanced aircraft. The missile system derives its name from the radar component of the missile system.

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Patriot stands for phased array tracking radar to intercept on target. It is now given the name anti-ballistic missile (ABM) system, which is its primary mission.

The Patriot system has four major operational functions: communication, command and control, radar surveillance and missile guidance. These functions combine to provide a coordinated, secure, integrated, mobile air defence system.

Patriot missile is equipped with a TVM guidance system. Target is acquired in the terminal phase of the flight by the target acquisition system in the missile. It transmits data using the TVM downlink via the ground radar to the engagement control station for computation of the final course correction. Course correction commands are transmitted to the missile via the missile track command uplink.

The missile has a range of 70km and maximum altitude greater than 24km. Minimum flight time, which is the time to arm the missile, is less than nine seconds, and the maximum flight time is less than 3½ minutes. It is a supersonic missile with maximum speed of Mach 5.

Different variants of Patriot missile system include MIM-104A, MIM-104B (PAC-1), MIM-104C (PAC-2), MIM-104D (PAC-2/GEM), MIM-104F (PAC-3) and Patriot Advanced Affordable Capability-4 (PAAC-4).

The missile system was inducted into service in 1981 and is in service till date. Other than the USA, a large number of other allied nations, including Egypt, Germany, Greece, Israel, Japan, Kuwait, the Netherlands, Saudi Arabia and Taiwan, have this system in their arsenal.

Patriot missile systems were first used during the Gulf War of 1991. There have been controversies about the success rate of the missile system in engaging ballistic missiles during the Gulf War. The system was again deployed in Iraq in 2003 during Operation Iraqi Freedom. The systems were stationed in Kuwait and were reportedly used with success against hostile ballistic missiles.

Recently, during Israel-Gaza conflict of 2014 called Operation Protective Edge, Patriot missile system was successfully used to bring down two unmanned aerial vehicle drones of Hamas. Fig. 6 shows Patriot missile launch.

AIM-54 Phoenix, manufactured by Hughes Aircraft Co. and Raytheon Corp. and capable of attacking more than one aircraft with multiple launches, is a supersonic, radar-guided, long-range air-to-air missile. The missile is carried in clusters of up to six missiles, and while in service during 1974 to 2004, it was used by the US Navy and Air Force of Islamic Republic of Iran.

F-14 Tomcat was the only launch platform capable of carrying AIM-54 Phoenix. The missile system retired from service in 2004 in favour of AIM-120 AMRAAM. This Mach 5 missile has a maximum operational range of 190km and employs a combination of semi-active (mid-course correction) and active radar homing guidance (terminal guidance).

AIM-120 AMRAAM (advanced medium-range air-to-air missile) is a high-supersonic, day/night/all-weather beyond-visual-range (BVR), fire-and-forget air-to-air missile. Manufactured by Hughes from 1991 to 1997 and Raytheon from 1997 till date, it has different variants, which include AIM-120A, AIM-120B, AIM-120C and AIM-120D, with AIM-120D having an operational range in excess of 180km. Operational ranges for other variants are 55km to 75km (AIM-120 A/B) and greater than 105km (AIM-120C).

It employs inertial navigation system (INS) for mid-course guidance and active radar homing for guidance in terminal phase. Once the missile closes to self-homing distance, the active radar guides it towards the target. This feature provides fire-and-forget capability to the missile and allows the pilot to fire a number of missiles simultaneously at multiple targets.


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